Crash test method and apparatus including pitch simulation

Abstract

A crash sled system for simulating the deceleration and pitching motion associated with vehicle crashes. A main sled is accelerated in accordance with vehicle deceleration that occurred during a crash event. A pitching platform is located above and moves with the main sled. Forward and rear guide assemblies are provided which are located along the sides of the pitching platform when the main sled and pitching platform are in the pre-launch position. When the main sled is launched, the front and rear ends of the pitching platform travel along paths established by the guide assemblies. Prior to launch, the guide assemblies are set to angles of inclination that provide linear approximations to paths for the forward and aft ends of the pitching platform that will result in pitching motion experienced by vehicles during the crash events being simulated. Variously configured guide assemblies are disclosed that provide design trade-off between simulation accuracy and system complexity.

The embododiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 
     
       1. A crash sled system for simulating deceleration and pitching motion associated with a vehicle crash comprising:
 a main sled configured for being catapulted from a pre-launch position and accelerated along a longitudinal path; 
 a pitching platform that is positioned above and configured for concurrent movement with the main sled; 
 front guide assemblies that extend along the forward end of each side of the main sled when the main sled is in a pre-launch position, each of the front guide assemblies defining a front path, the pitching platform having a forward end engaging the front guide assemblies for travel along the front paths; 
 one or more front guide actuators interconnected with each of the front guide assemblies, the one or more front guide actuators being operable for selectively positioning the front guide assemblies at a first predetermined inclination angle; 
 rear guide assemblies that extend along the aft end of each side of the main sled when the main sled is in the pre-launch position, each of the rear guide assemblies defining a rear path, the pitching platform having a rear end engaging the rear guide assemblies for travel along the rear paths; 
 one or more rear guide actuators interconnected with each of the rear guide assemblies, the one or more rear guide actuators being operable for selectively positioning the rear guide assemblies at a second predetermined inclination angle; and 
 wherein the first predetermined inclination angle and the second predetermined inclination angle are established with the main sled in the pre-launch position to determine pitching motion induced in the pitching platform during its concurrent movement with the main sled. 
 
     
     
       2. The crash sled system of  claim 1  wherein at least one of the front and rear paths is a substantially straight line path. 
     
     
       3. The crash sled system of  claim 2  wherein:
 the at least one substantially straight line path corresponds to a calculated reference path traveled by a first reference location to simulate at least one particular crash. 
 
     
     
       4. The crash sled system of  claim 3  wherein the at least one substantially straight line path is determined by linear regression of data that corresponds to the reference path. 
     
     
       5. The crash sled system of  claim 4  wherein the linear regression is a least-squares linear approximation. 
     
     
       6. The crash sled system of  claim 1  wherein at least one of the front and rear paths is non-linear. 
     
     
       7. The crash sled system of  claim 6  wherein the at least one non-linear path is a smooth curve. 
     
     
       8. The crash sled system of  claim 7  wherein:
 the at least one non-linear path corresponds to a calculated reference path traveled by a first reference location to simulate at least one particular crash. 
 
     
     
       9. The crash sled system of  claim 8  wherein the at least one non-linear path is determined by non-linear regression of data that corresponds to the reference path. 
     
     
       10. The crash sled system of  claim 1  wherein the forward and aft ends of the pitching platform include outwardly projecting guide members for travel along the front and rear paths, respectively, and wherein the system further comprises a pair of spaced apart A-frame assemblies, mounted to and extending upwardly at the forward end of the main sled with each A-frame assembly including a vertical slot, the forward end of the pitching platform being positioned between the A-frame assemblies, with the outwardly projecting guide members of the forward end of the pitching platform passing through the vertically extending slots of the A-frames for engagement with the forward guide assemblies. 
     
     
       11. The crash sled system of  claim 10  wherein the vertical slot of each A-frame includes oppositely disposed fore and aft walls and each A-frame assembly includes a slider block that is contained in the slot, the slider block being dimensioned and arranged for upward and downward movement in the slot, each outwardly projecting guide member at the forward end of the pitching platform extending through an associated slider block to allow limited upward and downward movement of the forward end of the pitching platform relative to the main sled. 
     
     
       12. The crash sled system of  claim 11  wherein:
 the guide members at the forward end of the pitching platform contact and slide along the front guide assemblies when the main sled is catapulted from the pre-launch position; and 
 the guide members at the aft end of the pitching platform contact and slide along the rear guide assemblies when the main sled is catapulted from the pre-launch position. 
 
     
     
       13. The crash sled system of  claim 12  wherein:
 the front guide assemblies, the one or more front guide actuators interconnected with each of the front guide assemblies, the rear guide assemblies, and the one or more rear guide actuators interconnected with each of the rear guide assemblies are mounted to the foundation that supports the crash sled system; and 
 the guide members at the forward and aft end of the pitching platform pass free of contact with the front and rear paths upon completion of the pitching simulation. 
 
     
     
       14. The crash sled system of  claim 13 , further comprising forward and aft brake units for restraining rotational movement of the pitching platform when the guide members at the forward and aft ends of the pitching platform pass free of contact with the front and rear paths of the front and rear guide assemblies. 
     
     
       15. The crash sled system of  claim 14  wherein:
 a forward brake unit for restraining rotational movement of the pitching platform is mounted to the top of the slider block of each A-frame, each forward brake unit including pistons for asserting braking force against the oppositely disposed fore and aft walls of the A-frame vertical slot; and 
 the aft brake unit includes brake bars that are mounted at the rear end of the pitching platform, the brake bars being spaced apart from one another and extending downwardly from the aft end of the pitching platform, the aft brake unit further including spaced apart brake modules for receiving and at least partially surrounding the brake bars, the brake modules including pistons for asserting a braking force on the brake bars. 
 
     
     
       16. The crash sled system of  claim 15  wherein:
 the forward brake units assert a substantially constant braking force both when the guide members at the forward end of the pitching platform are moving along the front paths and when the guide members pass free of the front paths of the front guide assemblies, the substantially constant braking force of the forward brake units not being large enough to overcome the reaction force asserted by the front guide assemblies while the guide members at the front of the pitching platform are moving along the front paths of the front guide assemblies but being large enough to stop movement of the front end of the pitching platform when the guide assemblies pass from the front paths; and 
 the aft brake units assert a substantially constant braking forces both when the guide members at the aft end of the pitching platform are moving along the rear paths of the aft guide assemblies and when the guide members pass free of the rear paths, the substantially constant braking force of the aft brake units not being large enough relative to overcoming the reaction force asserted by the rear guide assemblies while the guide members at the aft end of the pitching platform are moving along the rear paths of the rear guide assemblies but being large enough to stop movement of the aft end of the pitching platform when the guide assemblies pass from the rear paths. 
 
     
     
       17. The crash sled system of  claim 11  wherein:
 the guide members at the forward end of the pitching platform include rollers that travel along the front paths of the front guide assemblies when the main sled is catapulted from the pre-launch position; and 
 the guide members at the aft end of the pitching platform include rollers that travel along the rear paths of the rear guide assemblies when the main sled is catapulted from the pre-launch position. 
 
     
     
       18. The crash sled system of  claim 17  wherein:
 the front guide assemblies, the one or more front guide actuators interconnected with each of the front guide assemblies, the rear guide assemblies, and the one or more rear guide actuators interconnected with each of the rear guide assemblies mounted to the foundation that supports the crash sled system; and 
 the guide member rollers at the forward and aft end of the pitching platform pass free of contact with the front and rear paths upon completion of the pitching simulation. 
 
     
     
       19. The crash sled system of  claim 17 , further comprising forward and aft brake units for restraining rotational movement of the pitching platform when the rollers at the forward and aft ends of the pitching platform pass free of contact with the guide paths of the front and rear guide assemblies. 
     
     
       20. The crash sled system of  claim 17  wherein:
 a forward brake unit for restraining rotational movement of the pitching platform is mounted to the top of the slider block of each A-frame, each forward brake unit including pistons for asserting braking force against the oppositely disposed fore and aft walls of the A-frame vertical slot; and 
 the aft brake unit includes brake bars that are mounted at the rear end of the pitching platform, the brake bars being spaced apart from one another and extending downwardly from the rear end of the pitching platform, the aft brake unit further including spaced apart brake modules for receiving and at least partially surrounding the brake bars, the brake modules including pistons for asserting a braking force on the brake bars. 
 
     
     
       21. The crash sled system of  claim 20  wherein:
 the forward brake units assert a substantially constant braking force both when the guide members at the forward end of the pitching platform are moving along the front paths and when the guide members pass free of the front paths of the front guide assemblies, the substantially constant braking force of the forward brake units not being large enough to overcome the reaction force asserted by the front guide assemblies while the guide members at the front of the pitching platform are moving along the front paths of the front guide assemblies but being large enough to stop movement of the front end of the pitching platform when the guide assemblies pass from the front paths; and 
 the aft brake units assert a substantially constant braking force both when the guide members at the aft end of the pitching platform are moving along the rear paths of the aft guide assemblies and when the guide members pass free of the rear paths of the aft guide assemblies, the substantially constant braking force of the aft brake units not being large enough relative to overcoming the reaction force asserted by the rear guide assemblies while the guide members at the aft end of the pitching platform are moving along the rear paths of the rear guide assemblies but being large enough to stop movement of the aft end of the pitching platform when the guide assemblies pass from the rear paths. 
 
     
     
       22. The crash sled system of  claim 11  wherein at least a portion of the aft wall of the vertical slot of each A-frame assembly is covered with a liner and the region of the slider block facing the liner includes teeth projecting toward the liner, the yield strength of the liner being high enough that the teeth pass along the liner during normal operation of the crash sled and being low enough that the teeth engage the liner and apply a braking force to the forward end of the pitching platform in the event the main sled is being abruptly stopped.